In vivo Quantification of Corneocyte Lipids by Image Analysis

May 4, 2009 | Contact Author | By: David Boudier, Nathalie Guichard, Josselin Breugnot, Maud Le Guillou and Brigitte Closs, Silab
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Keywords: stratum corneum | quantification | fluorescence | lipids | image analysis

Abstract: In a new method described here by the authors, fluorescence emitted from samples and captured by image analysis is used to quantify the number of lipids present in the cornified cell envelope. This in vivo approach is fast and noninvasive and could be used to screen molecules for potential moisturizing and restructuring effects.

The lipids of the stratum corneum (SC) are composed mainly of cholesterol, free fatty acids and ceramides that are derived from the secretion of lamellar body (LB) contents at the stratum granulosum/SC interface. This secretion process occurs immediately prior to loricrin cross-linking into the cornified envelope (CE).1 One of the most important events in the homeostasis of the epidermis is the acquisition of hydrophobicity by covalent attachment of these lipids to the extracellular surface of CE components.2 In 2001, Hirao et al.3 developed a noninvasive method to evaluate the quality of this hydrophobic assembly by obtaining corneocytes via tape stripping and staining them with fluorescent Nile red. This qualitative approach enabled researchers to characterize the degree of maturation of the CE. Using this method, the reviewers also showed notable differences in terms of morphology and fluorescence distribution into corneocytes between various anatomical sites. However, a quantitative method to evaluate the emitted fluorescence from the samples was necessary since this fluorescence is representative of the total hydrophobicity of the CE due mainly to lipids covalently bound to proteins in the CE.

Recent developments in image detectors have made it possible to investigate biological structures. The number of computerized assessment technologies has increased, in turn facilitating and improving digital visualizations, assessment processing and analysis images. In some cases, the information sought can be obtained by simple visualization—i.e., in silico techniques—but more precise research involving the quantification of data often requires distinguishing the anatomical structures or “objects of interest” that form and are present in the images; this is generally a difficult stage called the segmentation of image.